body, html {
    margin: 0;
    padding: 0;
    height: 100%;
}

#container {
    height: 100%;
    display: flex;
}

#tool-box {
    display: block;
    background: #a8dc47;
    width: 100%;
    height: 50%;
    float: left;
    margin-top: 250px;
    /* margin-bottom: auto; */
}

#sidebar {
    display: block;
    background: #a8dc47;
    width: 10%;
    height: 100%;
    float: left;
}

#preview {
    background: #f9f9f9;
    width: 90%;
    height: 100%;
    float: right;
}

#viewer {
    background: #fff;
    width: 100%;
    height: 100%;
}

#tool-box button {
    margin-left: auto;
    margin-right: auto;
    display: block;
    background: #ccc;
    margin-top: 10px;
    margin-bottom: 5px;
    text-align: center;
    padding: 3px 3px;
    position: relative;
}